Various methods exist for estimating the air in an internal combustion engine. One conventional method uses measurements from a mass airflow sensor to estimate an air value. Another conventional method uses speed density calculations to estimate the value.
The first method is shown to be inaccurate during movement of cam phasers coupled to intake and exhaust camshafts of the engine. The second method provides more accurate estimation during transient operating conditions of the cam phasers. Conventional methods of estimating air lack the ability to detect a transient operating condition or a steady state operating condition of the cam phasers and lack the ability to apply the proper air estimation method during the transient operating condition.